Silk screen printing press



May 17, 1960 ca. v. HALL SILK SCREEN PRINTING PRESS 4 Sheets-Sheet 1Filed May 13, 1955 INVENTOR. GAAD/YE/P l HALL BY X/SiMaZ ,4 TTOR/YEK May17, 1960 Filed May 13, 1955,

G. v. HALL 2,936,705

SILK SCREEN PRINTING PRESS 4 Sheets-$heet 2 J6 d5 /Z7 a2 fdg 49 fee 3062 '5 f I I: v 0? W 1 E 59 59 6/ 07 72 46 46 45 9e 4 9 I 42 I7 I Z5 2842 i l I 9 A V I o V l8 35 32 26 ""fl'h 5/ i INVENTOR.

Z GARDNER V. HALL G. v. HALL 2,936,705

SILK SCREEN PRINTING PRESS May 17, 1960 Filed May 13, 1955 4Sheets-Sheet 3 99 J uvmvrox. bi [fl/ .0 n. U 93 GARDNER l HALL BY:saznkw-(Z.

K I W n z ATTORNEY.

SILK SCREEN PRINTING PRESS Gardner V. Hall, Des Moines, Iowafassigriorto Pace Mfg. Co., Des Moines, Iowa, a corporation of Iowa ApplicationMay 13, 1955, Serial No. 508,130

3 Claims. (Cl. 101- 123) This invention relates generally to printingpresses and more particularly to a silk screen printing press.

An object of this invention is to provide an improved silk screenprinting press.

A further object of this invention is to provide a silk screen printingpress which :can be used either for a regular printing operation or'a'flood printing operation.

Another object of this invention is to provide a silk plate 29 extendedtransversely of the main frame 21 screen printing presswhich includes ascreen mounted for up and down movement relative'to the material to beprinted upon and a squeegee member movable across the screen in a timedrelation with the up and down movement of the screen.

Still another object of this inventionis to provide a Fig. 1 is a sideelevational view of the printing press of this invention showing thechase therefor in a raised position, with some parts broken away'andother parts shown in section for the purpose of clarity;

Fig. 2 is an enlarged diagrammatic view of a portion of the printingpress of this invention, showing a moved position of the squeegeesupporting frame at the rear end of the stroke therefor;

Fig. 3 is a top plan view of the printing press of this invention in theposition shown in Fig. 1;

Fig. 4 is an enlarged side elevational view of a portion of the printingpress. of this invention, showing a moved position .of the squeegeesupporting frame. at .the front end of the stroke therefor during a.flood'printing operation; U 7 1 Fig. 5 is an enlarged side elevationalview illustrated similarly to Fig. 4 and showing the position .ofgthesqueegee supporting frame during a regular printing operation; g V

Fig. 6 is a diagrammatic view showing the path of travel of the squeegeein a regular printing operation;

Fig 7 is a diagrammatic view showing the path of travel of the squeegee'in a flood printing operation;

Fig. 8 is a bottom view of the bed frame inthe printing press of thisinvention showing the centering devices carried thereby and thedepending material supporting structure engaged by the centeringdevices;

Fig. 9 is an "enlarged top plan view of one of the cent ering devicesshown in Fig. 8, with some "parts broken 2,936,705 Patented May 17, 1960ice away and other parts shown in section for the purpose of clarity;

Fig. 10 is an enlarged top plan view, illustrated similarly to Fig. 9 ofanother one of the centering devices shown in Fig. 8;

Fig. 11 is an end view of a centering device; and

Fig. 12 is a fragmentary sectional view looking along the line 12'12 inFig. l.

' With reference to the drawing, the printing press of this invention,indicated generally at 20, is illustrated in Fig. 1 as including a mainframe 21 for supporting an inclined bed frame 22 for holding a sheetmaterial which is to be printed. For convenience of description, the end23 of the main frame 21 will be referred to hereinafter as the front endof the machine 20 and the opposite end 24 will be referred to as therear end of the machine. Pivotally supported on a shaft 26, arrangedtransversely of the bed frame 22, is a screen supporting frame or chase27 which extends forwardly from the shaft 26. A squeegee supportingframe 30 is movably mounted on the chase 27 for back and forth movementthereon. The driving mechanism A motor 28 (Figs. land 3), carried on asupporting below the bed frame 22, drives a shaft 16 for a gearreduction unit 17. A second shaft 18 for the unit '17 drives a sprocketWheel '31 secured to the shaft 26 for rotation in a counter-clockwisedirection as viewed in Fig. 1. A cam 32, secured to the shaft 26,engages a follower roller 33 carried on one end of a link member 34. Theopposite end of the link 34 is pivoted at 37 to an upright bracket 38secured to themotor supporting plate 29. A link '39, rigidly connectedto the link'34 is pivotally connected to'one end of a link 41, the opposite end of which is pivotally connected at 36 to the chase 27. Y

It is seen, therefore, that on rotation of the cam 32, with the,enlarged side 35 thereof in contact with the roller 33, the chase 27 ismaintained in a raised position by the links 34, 39 and 41. Acounterweight 55, secured to and extended rearwardly from the chase 27and positioned on the opposite side of the shaft 26 facilitates themaintaining of the chase 27 in araised position.

The weight of the chase 27 provides for a following movement of theroller 33 along the small side 40 of the, cam 32 in the lowered positionof the chase 27. In response to rotation of the follower 33 on inclinedportions 45 of the cam 32, the chase 27 is moved upwardly and downwardlyduring predetermined portions of the rotation of the cam 32. By virtueof the shape of the cam 32, with the substantially constantdiameter sideportions 35 and 40, and the relatively short inclined pordowndirectionsabout the shaft 26 relatively quickly and is maintained in an up or downposition for a predetermined time period. In a down position, the chase27 is parallel to and adjacent the bed frame 22 for print:

22 and a next piece of stock material to a predetermined angularrelation with the cam 32, are

a pair of crank arms 42, arranged outwardly of the bed frame22. A pairof links-43, corresponding to the crank arms 42, are pivotally connectedto and extend'between the crank arms 42 and the squeegee frame 30 toprovide for driving of the frame 30 in directions longitudinally of thechase.27, in responseto a rotation of theorem:

arms42. j r

It is seen, therefore, that upon rotation of the shaft 26, the chase 27is rocked up and down about the-shaft 26 and the squeegee frame 30 isconcurrently moved back and forth along the chase 27. By virtue of thepredetermined angular relation of the crank arms 42 and the cam 32, thechase 27 is in a down position during travel of the squeegee frame 30toward the front end 23 of the machine 20. During a return movement ofthe frame 30 toward the rear end 24 of the machine 20, the chase 27 isin an up position spaced above the bed frame By virture of the downwardmovement of the chase 27 at a time correspondingf to the reversal of thedirection of travel of the squeegee frame 30, the frame 30 ismomentarily maintained in a substantially stopped position on the chase27. In other words the links 43, which move the frame 30 on the chase27, are travelling upwardly from a dead center relation with the cranks42 at a time when the chase 27 is moving downwardly. As a result, thedownward rotational movement of the chase 27 compensates for the upwardrotational movement of the links 43 to provide for a stopped position.of the frame 30 on the chase 27 during the time the chase 27 is movingdownwardly.

The squeegee supporting frame As best appears in Figs. 1 and 3 thesqueegee supporting frame 30 includes a pair of rectangular end plateschase 27 and the screen 67 on swinging movement of the support units 53about the pivots 57 therefor. Stated otherwise, on downward swingingmovement of the units 53, as viewed in Fig. 1, the plate 63 is moveddownwardly toward the screen 67. As best appears in Figs. 4 and 5, inthe engaged positions of the units 53 with the stop pins 61, thesqueegee blade 66 is spaced above the screen 67.

For maintaining the plate 63 in a downwardly moved positioncorresponding to a position of the squeegee 66 in wiping engagement withthe screen 67, a hook 68 (Figs. 2, 4 and 5), provided on one of the endplates 46 is engaged with an inwardly directed pin 69 on one 46connected together by a pair of spacer bars 48 exeach end plate 46 arepositioned on opposite sides of the top flange 52 for the correspondingframe member 49 to provide for a longitudinal rolling movement of thesqueegee frame on the chase 27.

A supporting unit 53 (Figs. 1, 4 and 5), consisting of a pair ofpivotally connected scissor members 54 and 56, is mounted on the outerside of each end plate 46. The scissor members 54 and 56 in a unit 53are pivotally connected by a transverse pivot 57 extended through theadjacent end plate 46 for pivotally supporting the unit 53. Each member54 is of a reduced thickness adjacent the pivot 57 (Fig. 12) to thusform a stop 58 which is engaged with the. cooperating member 56 to limitpivotal movement of the members 54 and 56 in directions toward eachother. A spring 59 extended between the member 54 in a unit 53 and atransversely extended stop pin 61 on the adjacent end plate 46 biasesthe unit 53 into engagement with the stop pin 61. The spring 59 alsomaintains the members 54 and 56 in a unit 53 in positions in which thestop 5.8 engages the member 56.

A spring 62 extended between the free ends of the members 54 and 56, ina supporting unit, 53, further biases the scissor members 54 and 56toward the closed position in which the member 56 engages the stop 58.As will more clearly appear herein, the members 54 and 56 are maintainedin a closed position during operation of the machine 20. However, forsafety. purposes, the members 54 and 56 are movable in directions awayfrom each other against the action of the springs 59 and 62 when itbecomes necessary. For a purpose to appear later, a roller 65 is carriedon an inwardly extended shaft 70 on the free end of each of the members54.

A'supporting plate 63 (Figs. 1 and 3), secured to and extended betweenthe free ends of the scissor members 56 adjustably supports a woodenholder 64 for a depending squeegee blade 66 formed of a flexiblematerial such as rubber or the like. In one position of the plate 63,the holder 64 is vertically adjusted on the plate 63 to provide for adesired wiping engagement of the squeegee 66 with the silk screen 67carried by the chase 27 at a position below the squeegee 66.

It is apparent that the plate 63 and the squeegee 66 carried thereby arevertically movable relative to the of the scissor members 56. The hook68 is positioned between the plate 46 and the member 56 and is securedto a pivot 71 journaled in and extended through the end plate 46. AnL-shape lever 72 secured to the pivot 71 at a position inwardly of theplate 46 acts as a counterweight biasing the hook 68 toward a positionengaged with the pin 69. The curved top end 60 of the hook 68 providesfor a forward movement of the book 68 on the engagement thereof by thepin 69, as the pin 69 moves downwardly. The hook 68 is thus movableforwardly and then rearwardly to an engaged position on the pin 69, ondownward movement of the pin 69. On rotation of the lever 72 in aclockwise direction as viewed in Fig. 2, the hook" 68 is movable out ofan engaged position on the pin 69.

A roller 76 is provided on the free end 77 of the lever 72 for a purposeto appear later. A spring 78, loosely extended between an endplate 46and the lever 72 acts to return the lever 72 to a position resting onone of the spacer bars 48.

A dog 73 (Figs. 4 and 5), pivoted at 75 to the lower end of the hook 68is movable into engagement with the lower end 74 of the hook 68 onrearward movement of the dog 73 relative to the hook 68. On furtherrearward movement of the dog 73, the hook 68 is moved forwardly off thepin 69. By virtue of the location of the pivot 75 adjacent the forwardside of the hook 68, the dog 73'is freely movable in a forward directionwithout affecting the position of the hook 68.

vIt is apparent, that. on movement of the hook 68 01f the pin 69, theplate 63 is moved by the springs 59 to a stop. position corresponding tothe engaged position of the units 53 with the stop pins 61.

It. is seen, therefore, that the squeegee blade 66 is movable bothlongitudinally of the screen 67 and up and. down relative to the screen67.

An upper position of the squeegee 66, corresponding to the. engagementof the supporting units 53 with the stop pins 61 on the end plates 46,provides for a location of thesqueegee 66 spaced above the screen 67 Thelower position of the squeegee 66 in engagement with the screen 67corresponds to a downwardly moved position of the units 53 whichposition is maintained by the engagement of the hook 68 with the pin 69.Upward rotation of the lever 72 or rearward movement of the dog 73operates to disengage the hook 68 from the pin Mechanism for moving thesqueegee blade up and down relative to the silk screen During theoperation of the machine 20 the squeegee blade 66 is moved up and downrelative to the silk screen 67 at. predetermined intervals during thetravelof the squeegee 66 back and forth along the chase 27. Forconvenience. in describing the position of the blade 66 relative to the.chase 27, the position of the squeegee 66 at the rear end of the screen67 will be referred to as constituting, the rear end of the stroke ofthe squeegee 66.. The. position of the squeegee 66 adjacent the frontend 23 of the machine 20 will be referred to as the front end of thestroke of the squeeege 66.

For moving the squeegee 66 downwardly to a. position in engagement withthe screen 67 at the rear end of, the stroke, downwardly and rearwardlyinclined earns 81 are secured to and extended downwardly from the chaseside frame members -49 at positions spaced forwardly of the chase rearend frame member 80 (Figs. 1 and 3). The earns 81 are engaged by therollers 65 on the support units 53. On rearward movement of the rollers65 into contact with the cams 81, the rollers 65 are moved downwardly,by virtue of the downward inclination of the cams 81, to in turn movethe units 53 and the squeegee 66 downwardly to a position in which thehook 68 is engaged on the pin 69. i

- An outwardly projected plate 82 (-Figs. 1, 4 and 5) arranged on achase side frame member 49, intermediate the ends thereof, engages thedog 73 prior to the movement of the squeegee 66 to the forward end ofthe stroke therefor. On engaging the plate 82, the dog 73 ads todisengage the hook 68 from the pin 69. ln rresponseto suchdisengagement, the squeegee 66 is quickly moved upwardly by the springs59 out of contact with the screen 67.

Pivotally supported at 84 (Figs. 1, 4 and 5) on a block 87 secured tothe side frame member 49 at .a position forwardly of. the plate 82, is acam 83 having an inclined face 85. A handle 86 secured to the cam 83facilitates the manual movement of the cam 83 between the generallyhorizontal position A (Fig. 5) and the generally vertical position B(Fig. 4). A stop pin 88 on the block 87 engages the cam 83' to definethe positions A and B.

In the position A, the cam 83 is in a clearance relation with all of theparts of the squeegee frame-30 so as not to affect the movement thereof.

In the position B the inclined face 85 of the cam 83 is engaged by oneof the rollers 65 during the forward travel of the squeegee frame 30. Asa result of the downward and forwardinclination of the face 85, theroller 65 moves downwardly and forwardly along the face 85 to in turnmove the supporting units 53 downwardly to a position in which the pin59 is engaged by the hook 63 on an end plate 46. The hook 68 maintainsthe units 53 and the. squeegee 66 in a down position during rearwardtravel of the squeegee 66.

A11 L-Shape member 91 (Figs. 1 and 2), secured to one of the chase sideframe members 49 at a position between the chase end frame member 80 andthe crank arm 42, extends forwardly therefrom and has an 'upwardly andrearwardly inclined cam face 92 at its forward end; During rearwardtravel of the squeegee 66,

the roller 76' on the hook operating lever 72 travels upwardly on thecam face 92 prior tothe above described engagement of the rollers 65with the cams 81.

I -In response to the upward travel of the roller 76 on the cam face 92,the lever 72 is rotated ina clockwise in an up position, the travel ofthe roller 76 on the.

.cam face 92 is without any effect on the position of the squeegee 66.

Immediately following the upward travel of the roller 76, the roller 65engages the cam 81 to provide for movement of the squeegee 66 to thedown position therefor.

"The operation of the machine for regular printing For a regularprinting operation using an opaque ink or paint, the squeegee 66 movesrearwardly'ina spaced relation with the screen 67 (Fig. 6). Whenthesqueegee 66 reaches a position above an accumulated reservoir of 67,the squeegee 66 is moved downwardly into thepaint reservoir 93 forforward travel in engagement with the screen 67 so as to force the paintthrough the screen 67. A masking or the like on the screen 67 providesfor the printing of the paint, forced through the screen 67, in apredetermined pattern on the sheet material (not shown) which isreleasably held on the bed frame 22. At the forward end of its stroke,the squeegee 66 is moved upwardly for rearward travel above the screen67. To set the machine 20 for a regular printing opera tion, the lever86, on the cam 83 is moved downwardly so that the cam 83 is in itsposition shown at A.

Assume that the chase 27 is in the raised position therefor illustratedin Figs. 1 and 3, in which case the squeegee supporting frame 30 ismoving rearwardly thereon, and the squeegee 66 is in the upper positionshown in Fig. 1. Immediately prior to reaching the rear end of thestroke for the squeegee 66, the roller 76 on the hook operating lever 72rides upwardly on the cam face 92 on the member 91 to swing the hook 68forwardly about the pivot 71 therefor. However, since the squeegee 66 isalready in'its up position, corresponding to the position of the pin 69above the hook 68, such.

to the fact that the angular movement of the crank arms 42 toreciprocate the squeegee frame 30 is negatived by the downward movementof the chase 27. i

The cams 81 act to feed or direct the rollers 65 to positions betweenthe outwardly projected flanges 94 of channel shaped track members 96carried on and arranged outwardly of the bed frame 22, on downwardmovement of the chase 27. Such downward movement 1 of the rollers 65provides for a corresponding downward movement of the support units 53and the squeegee 66. As a result, the pin 69 on one of the units 53 ,ismoved downwardly to a position in which the hook 68 on the adjacent endplate 46 is engaged therewithto maintain the squeegee 66 in a downposition in engagement with the screen 67. v

The rollers 65 then travel forwardly, riding on the underside of the toptrack flanges 94. As best appears in Fig. 5, in this position of therollers 65, the plate 63 is moving along the top side of the chase 27and cooperates with the rollers 65 to maintain the chase 27 in a downposition against the bed frame 22. As a result, a stationary position ofthe screen 67 on the chase 27 is assured during the forward printingstroke of the squeegee 66 to insure a uniform printing operation. In theevent the operators hand should enter between the chase 27 and the bedframe 22, the chase 27 is manually movable upwardly against the pressureof the springs 59 and 62 to free the operators hand.

The rollers 65 ride on the flanges 94 until they reach the forward ends97 of the tracks 96 at which time the rollers 65 are free to moveupwardly. Concurrently with the travel of the rollers 65 off the flanges94, the dog 73 is moved into engagement with the outwardly projectingplate 82 on the chase side frame member 49. By virtue of this engagementand the forward travel of the frame 30, the dog 73 is moved rearwardlyrelative. to the book 68 to swing the hook 68 off the pin 69. Thesprings 59 then operate to pull the units 53 upwardly to thus move thesqueegee 66 upwardly off the screen 67 at a position of the screen 67corresponding substantially,

to the rear side of the accumulated paint reservoir 99 at or paint 93(Fig; 6 at the rear end of the screen, 7 the front end of the screen67.?

The extent of forward movement of the squeegee 66 prior to such upwardmovement thereof is adjustable on manipulation of a slide plate 101(Fig. 1) on one of the top track flanges 94. The plate 101 1s sl1dablysup ported on the front end of the track 26 and 1s maintained in anadjusted position by the frictional contact of the plate 101 with aretaining strap 102 carrier by the track 96 and engaged with the topside of the plate 101. L The upwardly curved free end 103 of the plate101 facilitates manual adjustment of the plate 101 and travel of aroller 65 off the plate 101.

The slide plate 101 constitutes an adjustable extension of the trackflange 94. Until a roller 65 travels off the free end 103 of the plate101, the squeegee 66 is restrained against any upward movement. Thus,the slide plate 101 is adjusted to regulate the extent of movement ofthe squeegee 66 into the accumulated paint reservon 99 prior to araising of the squeegee 66 off of the screen 67 The frame 30 then movesforwardly with the squeegee 66 spaced above the screen 67 and the paintreservoir 99. Concurrently with this upward and forward movement of thesqueegee 66, the chase 27 is moved upwardly by the action of the cam 3-2on the follower 33. The frame 30' then moves rearwardly on the case 27in a position spaced above the screen 67 and with the chase 27 in araised position.

It can be seen, therefore, thatduring a regular printing operation, thesqueegee 66 operates to force paint through the screen 67 onto the stockmaterial (not shown) onthe bed frame 22 during the forward stroke of thesqueegee 66. During rearward travel of the squeegee 66, in a spacedrelation with the screen 67,- some paint may drip from the squeegee 66onto the screen 67. However, since opaque paint is being used, anyunevenness of paint on the screen 67 caused by this dripping will notaffect the appearance of the printed material.

The operation f the machine for a flood printin operation A floodprinting operation (Fig. 7) is normally used when a large area is beingprinted so that large amounts of paint must be forced through the screen67, or a transparent or reflective type paint is used which must beuniformly applied. 'For such a printing operation, paint is distributedover the screen 67 during rearward travel of the squeegee 66. In allother respects, a flood operation is identical to the regular printingoperation hereinbefore described.

' To set the machine 20 for a flood printing operation, the lever 86 onthe cam 83 is moved upwardly to move the cam 83 to its position B.

Assume that the chase 27 is in the down position. illustrated in Fig. 4and that the squeegee 66 is moving for-. Wardly. Further assume that thedog 73 has engaged the plate 82 and the rollers 65 have trtveled off thetrack flanges 94. The squeegee 66 has therefore moved upwardl'y 0d thescreen 67 and forwardly over the paint reservoir 99 concurrently withthe raising of the chase 27.

One of the rollers 65 then moves along the downwardly.

and forwardly inclined face 85 on the cam 33 to thus move the units 53downwardly to a position in which the hook 68 engages the pin 69. Thesqueegee 66 is thus lowered into the paint reservoir 99 concurrentlywith the beginning of the rearward stroke of the squeegee 66.

The squeegee 66 thus acts to evenly spread or distribute paint from thereservoir 99 over the screen 67 during rearward travel of the squeegee66. By virtue of the flexibility of the screen 67,. none of this paintisforced through the screen 67 by the squeegee 66. During printing, thescreen 67 is moved or flexed downwardly by the squeegee 66 into contactwith the rigidly supported stock material (not shown) on the bed frame22- to force paint through the screen 67 as the squeegee 66 moves along:

8 material to serve as a backing for the screen 67eliminate's anyforcing of paint through the screen 67 during rearward travel of thesqueegee 66.

Immediately prior to engagement of the rollers 65 with the cams 81 atthe rear end of the stroke of the squeegee 66, theroller 76 on the hookoperating lever 72 rides upwardly onthe cam face 92 on the member 91.The hook 68 is thus rotated forwardly to a position off the pin 69 tothus cause raising movement of the squeegee 66 at a positioncorresponding to the front side of the paint reservoir 93 at the rearend of the screen 67.

The squeegee 66 moves rearwardly above the paint reservoir 93 until itmoves downwardly into the paint reservoir 93 in response to a downwardtravel of the rollers 65 on the earns 81. The chase 27 moves downwardlyto feed the rollers 65 into the spaces between the track flanges 94 forforward travel of the squeegee 66 on the'screen 67 as above described inconnection with the regular printing operation.

It is seen, therefore, that in a flooding operation (Fig. 7) thesqueegee 66 travels-back and forth on the chase 27 in contact with thescreen 67 between the paint reservoirs 93 and 99. At the end of eachstroke, the squeegee 66 jumps over a paint reservoir for travel in theopposite the screen 67. The absence-ofv any such rigidly supported 715direction to spread such paint. relatively large amounts of printed isthus formed.

The centering devices A supporting structure 111 (Fig. 8) is mounted onthe bed frame 22 for holding the sheet material to be printed upon in a.fixed position. Retractible stop means (not shown) on the top side ofthe structure 111 provides for the positioning of sheet material in apredetermined location on the structure 111 for a printing operation.

a A depending rectangular frame 112, illustrated diagrammatically indotted lines in Fig. 8, secured to the A uniform application of paint tothe material being bottom side 113 of the structure 111 is spacedinwardly.

of the bed frame 22. The frame 112 is adjustably movable longitudinallyand transversely of the bed frame 22 to provide for a centering of the.sheet material on the structure 111 relative to the silk screen 67.Such centering provides for a printing on a predetermined portion of thesheet material.

For adjusting the position of the frame 112, three manually adjustablecentering devices 114 (Figs. 8 and 9) are secured to and extendedinwardly of the bed frame 22. Each device 114 is arranged substantiallyopposite a corresponding non-adjustable centering device 116 (Figs. 8and 10) also carried on and extended inwardly of the bed frame 22.

As best appears in Figs. 9 and 11 each device 114 includes aflatrectangular mounting plate 117 secured to the bed frame 22. Atubular cylinder member 118, of a rectangular shape in transversesection, is secured at its inner end 119 to the plate 117. Receivedwithin the opposite or outer end 121 of. the cylinder 118 is a pistonmember 1220f a rectangular shape in transverse section. The piston 122is of a size to provide for the free move ment thereof longitudinally ofthe cylinder 118.

A pair of short screws 123, removably mounted on transversely oppositesides of the piston 122, adjacent the inner end 124 thereof, arereceived in slots 126, only one of which is shown, extendedlongitudinally of the cylinder 118. Engagement of the screws 123 withthe cylinder 118 at the ends of the slots 126 limits the longitudinalmovement of the piston 122 within the cylinder 118.

An elongated screw 127, received within and extended longitudinallyofthe cylinder 118, is threadably received in a tapped opening 128 inthe inner end 124 of the piston 122. A tapered. head 129 on the screw127 is received within. a similarly tapered opening 131 in the mountingplate 117 and is positioned'against the bed frame 22.

It can thus be seen that on rotation of the screw 127 the piston: 122is: movable: longitudinally of the cylinder 118'.

For rotating the screw 127, a socket 132-for receiving a wrench. isformed in the screw head 129 at a position aligned with an opening (notshown) in the bed frame 22. To rotate the screw 127, the wrench isextended through the bed frame opening and positioned in the socket 132.

A roller 134 is rotatably mounted on a bolt 136 extended transverselythrough the piston 122 adjacent the outer end 137 thereof. projectsoutwardly of the piston end 137. a

A centering device 116 (Figs. 8 and is identical with a centering device114 except for the substitution of a compression spring 138 in a device116 for the screw 127 in a device 114. A spring 138, in a device 116, ispositioned within the cylinder 118 and extends between the plate 117 andthe inner end of an opening 141 in the piston 122. Like numerals areused, therefore, on the devices 116 to designate like parts on thedevices 114.

In use, a device 114 is assembled on the bed frame 122 opposite a device116, with the rollers 134 for such devices in engagement with thedepending frame 112. Also, the springs 138 for the devices 116 areinitially compressed sufficiently to provide for substantial expansionof the springs 138.

To adjust the position of the structure 111, the screws 127 for thedevices 114 are selectively rotated to provide for a movement of thestructure 111 to a desired position. It is apparent that on rotation ofa screw 127 in a direction to move the piston 122 thereon outwardly ofthe corresponding cylinder 118 the frame 112 is moved away from thepiston 122 and against the action of the spring 138 in the oppositedevice 116. On rotation of a screw 127 in the opposite direction, theframe 112 is moved in an opposite direction by a spring 138. To turn orrotate the frame 112 relative to the bed frame 22, the screws 127 foradjacent ones of the devices 114 are rotated in opposite directions.

The provision of the rollers 134 on the devices 114 and 116 reducesfriction between the devices 114 and 116 and the frame 112 and thusfacilitates adjustable movement of the frame 112 in contact with therollers 134.

From the above description, it is seen that this invention provides animproved silk screen printing press 20 which is useable both for aregular printing operation and a flood printing operation. By moving thecam 83 between the positions A and B therefor, the press 20 is readilychanged from one such operation to the other. Further, by virtue of theup and down movement of the chase 27 in a timed relation with themovement of the squeegee 66 on the screen 67, a press operator canreadily place material to be printed upon the bed frame 22 and removethe previously printed material.

Although the invention has been described with respect to a preferredembodiment thereof, it is to be understood that it is not to be solimited since changes can be made therein which are within the fullintended scope of this invention as defined by the appended claims.

I claim: 1. A silk screen printing press comprising a main frame, a bedframe for holding material to be printed upon, guide track means mountedon said bed frame, a screen supporting frame movably mounted on saidmain frame for up and down movement toward and away from said bed frame,a screen mounted on said supporting frame, guide flange means mounted onsaid bed frame, a squeegee adapted for co-action with said screen, andmeans mounting said squeegee for reciprocal movement across and parallelto the surface of said bed frame including a pair of units secured ateach end of said squeegee mounting means, each unit comprising a platereciprocally movable on one of said guide flanges, a pair of upper andlower scissors members pivotally connected together at one ends thereofto said plate, said As shown in Fig. 9 the roller 134 lower member forreciproml movement along said 'guide track means, first spring meansconnected between said scissors members whereby to maintain them in aclosed position relative each other and pivotally movable'about saidroller as. a unit, second spring means connected between said plate andsaid secondv member whereby to pivot said members as a unitand thus saidsqueegee downwardly toward the surface of said bed frame upon uppermember having a pin secured thereto, the free upward movement of. saidplate relative to said bed frame, and hook means connected to said plateand engageable with said pin whereby to pivot said members as a unit andthus said squeegee upwardly and away from the surface of said bed frameupon downward movement of said end plate relative to said bed frame.

2. A silk screen printing press comprising a main frame, a bed frame forholding material to be printed upon, guide track means mounted on saidbed frame, a screen supporting frame movably mounted on said main framefor up and down movement toward and away from said bed frame, a screenmounted on said supporting frame, guide flange means mounted on said bedframe, a squeegee adapted for co-action with said screen, and meansmounting said squeegee for reciprocal movement across and parallel tothe surface of said bed frame including a pair of units secured at eachend of said squeegee mounting means, each unit comprising a platereciprocally movable on one of said guide flanges, a pair of upper andlower scissors members pivotally connected together at their one ends tosaid plate, the upper member connected at its free end to said squeegeegee, roller means rotatably connecting the free end of the lower memberto said guide track means for recip rocal movement thereon, resilientmeans biasing the free ends of said members together whereby the membersare pivotally movable as a unit about said roller means to thus vary theposition of said squeegee relative to the; surface of said bed frame,spring means connected be tween said lower member and said plate wherebyupon:

upward movement of said plate relative to said bed.

frame, said spring means pivots said members as a unit: about saidroller means in a direction toward said bedi surface, and hook meansmounted on said plate: and engageable with said pin, wherebyupondownward. movement of said plate relative to said bed surface, said:

hook forceably rotates said members as a unit about said;

roller means in a direction away from said bed surface.

3. A silk screen printing press comprising a main: frame, a bedframe'for holding material to be printed upon, guide track means mountedon said bed frame, a; screen supporting frame movably mounted on saidmain frame for up and down movement toward and away from said bed frame,a screen mounted on said supporting frame, guide flange means mounted onsaid bed frame, a squeegee adapted for co-action with said screen; andmeans mounting said squeegee for reciprocal movement across and parallelto the surface of said bed frame including a pair of units secured ateach end of said squeegee mounting means, each unit comprising a platereciprocally movable on one of said guide flanges, a pair of memberspivotally connected to said plate whereby the free ends of said membersare movable in a scissors-like movement relative to each other, the freeend of one member connected to said squeegee and the free end of theother member movably mounted on said guide track means, means biasingsaid free ends toward; each other whereby said members are movable as a;closed unit about the free end of said other member, means connectedbetween said plate and said other mem' ber for biasing said members as aunit in a direction to move said squeegee toward the surface of saidbed. frame upon an upward movement of said plate relative to said bedframe, and hook means connected between said plate and said one memberwhereby to rotate said members as a unit in a direction away from saidsurface of said bed frame upon a downward movement of said 2,076,023Halsted Apr. 6, @937 plate relative to said bed frame. 2,263,966Greenleaf NOV, 25, 1941 References Cited in the file of this patentLouft May 1947 UNITED STATES PATENTS 5v 2,704,510 Walsh Mar. 22,19551,922,710 Owens Aug. 15', 1933 2,581,775 Wade Jan. 8, 1952

